/* load PNG with libspng
 *
 * 1/5/20
 * 	- from pngload.c
 * 19/2/21 781545872
 * 	- read out background, if we can
 * 29/8/21 joshuamsager
 *	-  add "unlimited" flag to png load
 * 3/2/23 MathemanFlo
 * 	- add bits per sample metadata
 */

/*

	This file is part of VIPS.

	VIPS is free software; you can redistribute it and/or modify
	it under the terms of the GNU Lesser General Public License as published by
	the Free Software Foundation; either version 2 of the License, or
	(at your option) any later version.

	This program is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
	GNU Lesser General Public License for more details.

	You should have received a copy of the GNU Lesser General Public License
	along with this program; if not, write to the Free Software
	Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
	02110-1301  USA

 */

/*

	These files are distributed with VIPS - http://www.vips.ecs.soton.ac.uk

 */

/*
#define DEBUG
 */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif /*HAVE_CONFIG_H*/
#include <glib/gi18n-lib.h>

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <vips/vips.h>
#include <vips/buf.h>
#include <vips/internal.h>

#include "pforeign.h"

#ifdef HAVE_SPNG

#include <spng.h>

typedef struct _VipsForeignLoadPng {
	VipsForeignLoad parent_object;

	/* Set by subclasses.
	 */
	VipsSource *source;

	/* Remove DoS limits.
	 */
	gboolean unlimited;

	spng_ctx *ctx;
	struct spng_ihdr ihdr;
	enum spng_format fmt;
	int bands;
	VipsInterpretation interpretation;
	VipsBandFormat format;
	int y_pos;
} VipsForeignLoadPng;

typedef VipsForeignLoadClass VipsForeignLoadPngClass;

G_DEFINE_ABSTRACT_TYPE(VipsForeignLoadPng, vips_foreign_load_png,
	VIPS_TYPE_FOREIGN_LOAD);

static void
vips_foreign_load_png_dispose(GObject *gobject)
{
	VipsForeignLoadPng *png = (VipsForeignLoadPng *) gobject;

	VIPS_FREEF(spng_ctx_free, png->ctx);
	VIPS_UNREF(png->source);

	G_OBJECT_CLASS(vips_foreign_load_png_parent_class)->dispose(gobject);
}

static int
vips_foreign_load_png_stream(spng_ctx *ctx, void *user,
	void *dest, size_t length)
{
	VipsSource *source = VIPS_SOURCE(user);

	while (length > 0) {
		gint64 bytes_read;

		bytes_read = vips_source_read(source, dest, length);
		if (bytes_read < 0)
			return SPNG_IO_ERROR;
		if (bytes_read == 0)
			return SPNG_IO_EOF;

		dest = (char *) dest + bytes_read;
		length -= bytes_read;
	}

	return 0;
}

static VipsForeignFlags
vips_foreign_load_png_get_flags_source(VipsSource *source)
{
	spng_ctx *ctx;
	struct spng_ihdr ihdr;
	VipsForeignFlags flags;

	ctx = spng_ctx_new(SPNG_CTX_IGNORE_ADLER32);
	spng_set_crc_action(ctx, SPNG_CRC_USE, SPNG_CRC_USE);
	if (vips_source_rewind(source))
		return 0;
	spng_set_png_stream(ctx,
		vips_foreign_load_png_stream, source);
	if (spng_get_ihdr(ctx, &ihdr)) {
		spng_ctx_free(ctx);
		return 0;
	}
	spng_ctx_free(ctx);

	flags = 0;
	if (ihdr.interlace_method != SPNG_INTERLACE_NONE)
		flags |= VIPS_FOREIGN_PARTIAL;
	else
		flags |= VIPS_FOREIGN_SEQUENTIAL;

	return flags;
}

static VipsForeignFlags
vips_foreign_load_png_get_flags(VipsForeignLoad *load)
{
	VipsForeignLoadPng *png = (VipsForeignLoadPng *) load;

	return vips_foreign_load_png_get_flags_source(png->source);
}

static VipsForeignFlags
vips_foreign_load_png_get_flags_filename(const char *filename)
{
	VipsSource *source;
	VipsForeignFlags flags;

	if (!(source = vips_source_new_from_file(filename)))
		return 0;
	flags = vips_foreign_load_png_get_flags_source(source);
	VIPS_UNREF(source);

	return flags;
}

/* Set the png text data as metadata on the vips image. These are always
 * null-terminated strings.
 */
static void
vips_foreign_load_png_set_text(VipsImage *out,
	int i, const char *key, const char *value)
{
#ifdef DEBUG
	printf("vips_foreign_load_png_set_text: key %s, value %s\n",
		key, value);
#endif /*DEBUG*/

	if (strcmp(key, "XML:com.adobe.xmp") == 0) {
		/* Save as an XMP tag. This must be a BLOB, for compatibility
		 * for things like the XMP blob that the tiff loader adds.
		 *
		 * Note that this will remove the null-termination from the
		 * string. We must carefully reattach this.
		 */
		vips_image_set_blob_copy(out,
			VIPS_META_XMP_NAME, value, strlen(value));
	}
	else {
		char name[256];

		/* Save as a string comment. Some PNGs have EXIF data as
		 * text segments, unfortunately.
		 */
		vips_snprintf(name, 256, "png-comment-%d-%s", i, key);

		vips_image_set_string(out, name, value);
	}
}

static int
vips_foreign_load_png_set_header(VipsForeignLoadPng *png, VipsImage *image)
{
	double xres, yres;
	struct spng_iccp iccp;
	struct spng_exif exif;
	struct spng_phys phys;
	struct spng_bkgd bkgd;
	guint32 n_text;

	/* Get resolution. Default to 72 pixels per inch.
	 */
	xres = 72.0 / 25.4;
	yres = 72.0 / 25.4;
	if (!spng_get_phys(png->ctx, &phys)) {
		/* unit 1 means pixels per metre, otherwise unspecified.
		 */
		xres = phys.unit_specifier == 1
			? phys.ppu_x / 1000.0
			: phys.ppu_x;
		yres = phys.unit_specifier == 1
			? phys.ppu_y / 1000.0
			: phys.ppu_y;
	}

	vips_image_init_fields(image,
		png->ihdr.width, png->ihdr.height, png->bands,
		png->format, VIPS_CODING_NONE, png->interpretation,
		xres, yres);

	VIPS_SETSTR(image->filename,
		vips_connection_filename(VIPS_CONNECTION(png->source)));

	if (vips_image_pipelinev(image, VIPS_DEMAND_STYLE_THINSTRIP, NULL))
		return -1;

	if (!spng_get_iccp(png->ctx, &iccp))
		vips_image_set_blob_copy(image,
			VIPS_META_ICC_NAME, iccp.profile, iccp.profile_len);

	if (!spng_get_text(png->ctx, NULL, &n_text)) {
		struct spng_text *text;

		/* Very large numbers of text chunks are used in DoS
		 * attacks.
		 */
		if (!png->unlimited && n_text > MAX_PNG_TEXT_CHUNKS) {
			g_warning(_("%d text chunks, only %d text chunks will be loaded"),
				n_text, MAX_PNG_TEXT_CHUNKS);
			n_text = MAX_PNG_TEXT_CHUNKS;
		}

		text = VIPS_ARRAY(VIPS_OBJECT(png),
			n_text, struct spng_text);
		if (!spng_get_text(png->ctx, text, &n_text)) {
			guint32 i;

			for (i = 0; i < n_text; i++)
				/* .text is always a null-terminated C string.
				 */
				vips_foreign_load_png_set_text(image,
					i, text[i].keyword, text[i].text);
		}
	}

	if (!spng_get_exif(png->ctx, &exif))
		vips_image_set_blob_copy(image, VIPS_META_EXIF_NAME,
			exif.data, exif.length);

	vips_image_set_int(image, VIPS_META_BITS_PER_SAMPLE,
		png->ihdr.bit_depth);

	if (png->ihdr.color_type == SPNG_COLOR_TYPE_INDEXED) {
		/* Deprecated "palette-bit-depth" use "bits-per-sample" instead.
		 */
		vips_image_set_int(image,
			"palette-bit-depth", png->ihdr.bit_depth);

		vips_image_set_int(image, VIPS_META_PALETTE, 1);
	}

	/* Let our caller know. These are very expensive to decode.
	 */
	if (png->ihdr.interlace_method != SPNG_INTERLACE_NONE)
		vips_image_set_int(image, "interlaced", 1);

	if (!spng_get_bkgd(png->ctx, &bkgd)) {
		const int scale =
			image->BandFmt == VIPS_FORMAT_UCHAR ? 1 : 256;

		double array[3];
		int n;

		switch (png->ihdr.color_type) {
		case SPNG_COLOR_TYPE_GRAYSCALE:
		case SPNG_COLOR_TYPE_GRAYSCALE_ALPHA:
			array[0] = bkgd.gray / scale;
			n = 1;
			break;

		case SPNG_COLOR_TYPE_TRUECOLOR:
		case SPNG_COLOR_TYPE_TRUECOLOR_ALPHA:
			array[0] = bkgd.red / scale;
			array[1] = bkgd.green / scale;
			array[2] = bkgd.blue / scale;
			n = 3;
			break;

		case SPNG_COLOR_TYPE_INDEXED:
		default:
			/* Not sure what to do here. I suppose we should read
			 * the palette.
			 */
			n = 0;
			break;
		}

		if (n > 0)
			vips_image_set_array_double(image, "background",
				array, n);
	}

	return 0;
}

static int
vips_foreign_load_png_header(VipsForeignLoad *load)
{
	VipsObjectClass *class = VIPS_OBJECT_GET_CLASS(load);
	VipsForeignLoadPng *png = (VipsForeignLoadPng *) load;

	int flags;
	int error;
	struct spng_trns trns;

	/* In non-fail mode, ignore CRC errors.
	 */
	flags = 0;
	if (load->fail_on < VIPS_FAIL_ON_ERROR)
		flags |= SPNG_CTX_IGNORE_ADLER32;
	png->ctx = spng_ctx_new(flags);
	if (load->fail_on < VIPS_FAIL_ON_ERROR)
		/* Ignore and don't calculate checksums.
		 */
		spng_set_crc_action(png->ctx, SPNG_CRC_USE, SPNG_CRC_USE);

	/* Set limits to avoid decompression bombs. Set chunk limits to 60mb
	 * -- we've seen 50mb XMP blocks in the wild.
	 *
	 * No need to test the decoded image size -- the user can do that if
	 * they wish.
	 */
	if (!png->unlimited) {
		spng_set_image_limits(png->ctx,
			VIPS_MAX_COORD, VIPS_MAX_COORD);
		spng_set_chunk_limits(png->ctx,
			60 * 1024 * 1024, 60 * 1024 * 1024);
	}

	if (vips_source_rewind(png->source))
		return -1;
	spng_set_png_stream(png->ctx,
		vips_foreign_load_png_stream, png->source);
	if ((error = spng_get_ihdr(png->ctx, &png->ihdr))) {
		vips_error(class->nickname, "%s", spng_strerror(error));
		return -1;
	}

#ifdef DEBUG
	printf("width: %d\nheight: %d\nbit depth: %d\ncolor type: %d\n",
		png->ihdr.width, png->ihdr.height,
		png->ihdr.bit_depth, png->ihdr.color_type);
	printf("compression method: %d\nfilter method: %d\n"
		   "interlace method: %d\n",
		png->ihdr.compression_method, png->ihdr.filter_method,
		png->ihdr.interlace_method);
#endif /*DEBUG*/

	/* Just convert to host-endian if nothing else applies.
	 */
	png->fmt = SPNG_FMT_PNG;

	switch (png->ihdr.color_type) {
	case SPNG_COLOR_TYPE_INDEXED:
		png->bands = 3;
		break;

	case SPNG_COLOR_TYPE_GRAYSCALE_ALPHA:
	case SPNG_COLOR_TYPE_GRAYSCALE:
		png->bands = 1;
		break;

	case SPNG_COLOR_TYPE_TRUECOLOR:
	case SPNG_COLOR_TYPE_TRUECOLOR_ALPHA:
		png->bands = 3;
		break;

	default:
		vips_error(class->nickname, "%s", _("unknown color type"));
		return -1;
	}

	/* Set libvips format and interpretation.
	 */
	if (png->ihdr.bit_depth > 8) {
		if (png->bands < 3)
			png->interpretation = VIPS_INTERPRETATION_GREY16;
		else
			png->interpretation = VIPS_INTERPRETATION_RGB16;

		png->format = VIPS_FORMAT_USHORT;
	}
	else {
		if (png->bands < 3)
			png->interpretation = VIPS_INTERPRETATION_B_W;
		else
			png->interpretation = VIPS_INTERPRETATION_sRGB;

		png->format = VIPS_FORMAT_UCHAR;
	}

	/* Expand palette images.
	 */
	if (png->ihdr.color_type == SPNG_COLOR_TYPE_INDEXED)
		png->fmt = SPNG_FMT_RGB8;

	/* Expand <8 bit images to full bytes.
	 */
	if (png->ihdr.color_type == SPNG_COLOR_TYPE_GRAYSCALE &&
		png->ihdr.bit_depth < 8)
		png->fmt = SPNG_FMT_G8;

	/* Try reading the optional transparency chunk. This will cause all
	 * chunks up to the first IDAT to be read in, so it can fail if any
	 * chunk has an error.
	 */
	error = spng_get_trns(png->ctx, &trns);
	if (error &&
		error != SPNG_ECHUNKAVAIL) {
		vips_error(class->nickname, "%s", spng_strerror(error));
		return -1;
	}

	/* Expand transparency.
	 *
	 * The _ALPHA types should not have the optional trns chunk (they
	 * always have a transparent band), see
	 * https://www.w3.org/TR/2003/REC-PNG-20031110/#11tRNS
	 *
	 * It's quick and safe to call spng_get_trns() again, and we now know
	 * it will only fail for no transparency chunk.
	 */
	if (png->ihdr.color_type == SPNG_COLOR_TYPE_GRAYSCALE_ALPHA ||
		png->ihdr.color_type == SPNG_COLOR_TYPE_TRUECOLOR_ALPHA)
		png->bands += 1;
	else if (!spng_get_trns(png->ctx, &trns)) {
		png->bands += 1;

		if (png->ihdr.color_type == SPNG_COLOR_TYPE_TRUECOLOR) {
			if (png->ihdr.bit_depth == 16)
				png->fmt = SPNG_FMT_RGBA16;
			else
				png->fmt = SPNG_FMT_RGBA8;
		}
		else if (png->ihdr.color_type == SPNG_COLOR_TYPE_INDEXED)
			png->fmt = SPNG_FMT_RGBA8;
		else if (png->ihdr.color_type == SPNG_COLOR_TYPE_GRAYSCALE) {
			if (png->ihdr.bit_depth == 16)
				png->fmt = SPNG_FMT_GA16;
			else
				png->fmt = SPNG_FMT_GA8;
		}
	}

	vips_source_minimise(png->source);

	if (vips_foreign_load_png_set_header(png, load->out))
		return -1;

	return 0;
}

static void
vips_foreign_load_png_minimise(VipsObject *object, VipsForeignLoadPng *png)
{
	vips_source_minimise(png->source);
}

static int
vips_foreign_load_png_generate(VipsRegion *out_region,
	void *seq, void *a, void *b, gboolean *stop)
{
	VipsRect *r = &out_region->valid;
	VipsForeignLoad *load = VIPS_FOREIGN_LOAD(a);
	VipsForeignLoadPng *png = (VipsForeignLoadPng *) load;
	VipsObjectClass *class = VIPS_OBJECT_GET_CLASS(png);

	int y;
	int error;

#ifdef DEBUG
	printf("vips_foreign_load_png_generate: line %d, %d rows\n",
		r->top, r->height);
	printf("vips_foreign_load_png_generate: y_top = %d\n", png->y_pos);
#endif /*DEBUG*/

	/* We're inside a tilecache where tiles are the full image width, so
	 * this should always be true.
	 */
	g_assert(r->left == 0);
	g_assert(r->width == out_region->im->Xsize);
	g_assert(VIPS_RECT_BOTTOM(r) <= out_region->im->Ysize);

	/* Tiles should always be a strip in height, unless it's the final
	 * strip.
	 */
	g_assert(r->height ==
		VIPS_MIN(VIPS__FATSTRIP_HEIGHT, out_region->im->Ysize - r->top));

	/* And check that y_pos is correct. It should be, since we are inside
	 * a vips_sequential().
	 */
	if (r->top != png->y_pos) {
		vips_error(class->nickname,
			_("out of order read at line %d"), png->y_pos);
		return -1;
	}

	for (y = 0; y < r->height; y++) {
		/* libspng returns EOI when successfully reading the
		 * final line of input.
		 */
		error = spng_decode_row(png->ctx,
			VIPS_REGION_ADDR(out_region, 0, r->top + y),
			VIPS_REGION_SIZEOF_LINE(out_region));
		if (error != 0 &&
			error != SPNG_EOI) {
			/* We've failed to read some pixels. Knock this
			 * operation out of cache.
			 */
			vips_operation_invalidate(VIPS_OPERATION(png));

#ifdef DEBUG
			printf("vips_foreign_load_png_generate:\n");
			printf("  spng_decode_row() failed, line %d\n",
				r->top + y);
			printf("  thread %p\n", g_thread_self());
			printf("  error %s\n", spng_strerror(error));
#endif /*DEBUG*/

			g_warning("%s: %s",
				class->nickname, spng_strerror(error));

			/* And bail if trunc is on.
			 */
			if (load->fail_on >= VIPS_FAIL_ON_TRUNCATED) {
				vips_error(class->nickname,
					"%s", _("libspng read error"));
				return -1;
			}
		}

		png->y_pos += 1;
	}

	return 0;
}

static int
vips_foreign_load_png_load(VipsForeignLoad *load)
{
	VipsObjectClass *class = VIPS_OBJECT_GET_CLASS(load);
	VipsForeignLoadPng *png = (VipsForeignLoadPng *) load;
	VipsImage **t = (VipsImage **)
		vips_object_local_array(VIPS_OBJECT(load), 3);

	enum spng_decode_flags flags;
	int error;

	if (vips_source_decode(png->source))
		return -1;

	/* Decode transparency, if available.
	 */
	flags = SPNG_DECODE_TRNS;

	if (png->ihdr.interlace_method != SPNG_INTERLACE_NONE) {
		/* Arg awful interlaced image. We have to load to a huge mem
		 * buffer, then copy to out.
		 */
		t[0] = vips_image_new_memory();
		if (vips_foreign_load_png_set_header(png, t[0]) ||
			vips_image_write_prepare(t[0]))
			return -1;

		if ((error = spng_decode_image(png->ctx,
				 VIPS_IMAGE_ADDR(t[0], 0, 0),
				 VIPS_IMAGE_SIZEOF_IMAGE(t[0]),
				 png->fmt, flags))) {
			vips_error(class->nickname,
				"%s", spng_strerror(error));
			return -1;
		}

		/* We've now finished reading the file.
		 */
		vips_source_minimise(png->source);

		if (vips_image_write(t[0], load->real))
			return -1;
	}
	else {
		t[0] = vips_image_new();

		if (vips_foreign_load_png_set_header(png, t[0]))
			return -1;

		/* We can decode these progressively.
		 */
		flags |= SPNG_DECODE_PROGRESSIVE;

		if ((error = spng_decode_image(png->ctx, NULL, 0,
				 png->fmt, flags))) {
			vips_error(class->nickname,
				"%s", spng_strerror(error));
			return -1;
		}

		/* Close input immediately at end of read.
		 */
		g_signal_connect(t[0], "minimise",
			G_CALLBACK(vips_foreign_load_png_minimise), png);

		if (vips_image_generate(t[0],
				NULL, vips_foreign_load_png_generate, NULL,
				png, NULL) ||
			vips_sequential(t[0], &t[1],
				"tile_height", VIPS__FATSTRIP_HEIGHT,
				NULL) ||
			vips_image_write(t[1], load->real))
			return -1;
	}

	return 0;
}

static void
vips_foreign_load_png_class_init(VipsForeignLoadPngClass *class)
{
	GObjectClass *gobject_class = G_OBJECT_CLASS(class);
	VipsObjectClass *object_class = (VipsObjectClass *) class;
	VipsForeignClass *foreign_class = (VipsForeignClass *) class;
	VipsForeignLoadClass *load_class = (VipsForeignLoadClass *) class;

	gobject_class->dispose = vips_foreign_load_png_dispose;
	gobject_class->set_property = vips_object_set_property;
	gobject_class->get_property = vips_object_get_property;

	object_class->nickname = "pngload_base";
	object_class->description = _("load png base class");

	/* We are fast at is_a(), so high priority.
	 */
	foreign_class->priority = 200;

	load_class->get_flags_filename =
		vips_foreign_load_png_get_flags_filename;
	load_class->get_flags = vips_foreign_load_png_get_flags;
	load_class->header = vips_foreign_load_png_header;
	load_class->load = vips_foreign_load_png_load;

	VIPS_ARG_BOOL(class, "unlimited", 23,
		_("Unlimited"),
		_("Remove all denial of service limits"),
		VIPS_ARGUMENT_OPTIONAL_INPUT,
		G_STRUCT_OFFSET(VipsForeignLoadPng, unlimited),
		FALSE);
}

static void
vips_foreign_load_png_init(VipsForeignLoadPng *png)
{
}

typedef struct _VipsForeignLoadPngSource {
	VipsForeignLoadPng parent_object;

	/* Load from a source.
	 */
	VipsSource *source;

} VipsForeignLoadPngSource;

typedef VipsForeignLoadPngClass VipsForeignLoadPngSourceClass;

G_DEFINE_TYPE(VipsForeignLoadPngSource, vips_foreign_load_png_source,
	vips_foreign_load_png_get_type());

static int
vips_foreign_load_png_source_build(VipsObject *object)
{
	VipsForeignLoadPng *png = (VipsForeignLoadPng *) object;
	VipsForeignLoadPngSource *source = (VipsForeignLoadPngSource *) object;

	if (source->source) {
		png->source = source->source;
		g_object_ref(png->source);
	}

	if (VIPS_OBJECT_CLASS(vips_foreign_load_png_source_parent_class)
			->build(object))
		return -1;

	return 0;
}

static gboolean
vips_foreign_load_png_source_is_a_source(VipsSource *source)
{
	static unsigned char signature[8] = { 137, 80, 78, 71, 13, 10, 26, 10 };

	const unsigned char *p;

	if ((p = vips_source_sniff(source, 8)) &&
		memcmp(p, signature, 8) == 0)
		return TRUE;

	return FALSE;
}

static void
vips_foreign_load_png_source_class_init(VipsForeignLoadPngSourceClass *class)
{
	GObjectClass *gobject_class = G_OBJECT_CLASS(class);
	VipsObjectClass *object_class = (VipsObjectClass *) class;
	VipsOperationClass *operation_class = VIPS_OPERATION_CLASS(class);
	VipsForeignLoadClass *load_class = (VipsForeignLoadClass *) class;

	gobject_class->set_property = vips_object_set_property;
	gobject_class->get_property = vips_object_get_property;

	object_class->nickname = "pngload_source";
	object_class->description = _("load png from source");
	object_class->build = vips_foreign_load_png_source_build;

	operation_class->flags |= VIPS_OPERATION_NOCACHE;

	load_class->is_a_source = vips_foreign_load_png_source_is_a_source;

	VIPS_ARG_OBJECT(class, "source", 1,
		_("Source"),
		_("Source to load from"),
		VIPS_ARGUMENT_REQUIRED_INPUT,
		G_STRUCT_OFFSET(VipsForeignLoadPngSource, source),
		VIPS_TYPE_SOURCE);
}

static void
vips_foreign_load_png_source_init(VipsForeignLoadPngSource *source)
{
}

typedef struct _VipsForeignLoadPngFile {
	VipsForeignLoadPng parent_object;

	/* Filename for load.
	 */
	char *filename;

} VipsForeignLoadPngFile;

typedef VipsForeignLoadPngClass VipsForeignLoadPngFileClass;

G_DEFINE_TYPE(VipsForeignLoadPngFile, vips_foreign_load_png_file,
	vips_foreign_load_png_get_type());

static int
vips_foreign_load_png_file_build(VipsObject *object)
{
	VipsForeignLoadPng *png = (VipsForeignLoadPng *) object;
	VipsForeignLoadPngFile *file = (VipsForeignLoadPngFile *) object;

	if (file->filename &&
		!(png->source = vips_source_new_from_file(file->filename)))
		return -1;

	if (VIPS_OBJECT_CLASS(vips_foreign_load_png_file_parent_class)->build(object))
		return -1;

	return 0;
}

static gboolean
vips_foreign_load_png_file_is_a(const char *filename)
{
	VipsSource *source;
	gboolean result;

	if (!(source = vips_source_new_from_file(filename)))
		return FALSE;
	result = vips_foreign_load_png_source_is_a_source(source);
	VIPS_UNREF(source);

	return result;
}

const char *vips_foreign_load_png_file_suffs[] = { ".png", NULL };

static void
vips_foreign_load_png_file_class_init(VipsForeignLoadPngFileClass *class)
{
	GObjectClass *gobject_class = G_OBJECT_CLASS(class);
	VipsObjectClass *object_class = (VipsObjectClass *) class;
	VipsForeignClass *foreign_class = (VipsForeignClass *) class;
	VipsForeignLoadClass *load_class = (VipsForeignLoadClass *) class;

	gobject_class->set_property = vips_object_set_property;
	gobject_class->get_property = vips_object_get_property;

	object_class->nickname = "pngload";
	object_class->description = _("load png from file");
	object_class->build = vips_foreign_load_png_file_build;

	foreign_class->suffs = vips_foreign_load_png_file_suffs;

	load_class->is_a = vips_foreign_load_png_file_is_a;

	VIPS_ARG_STRING(class, "filename", 1,
		_("Filename"),
		_("Filename to load from"),
		VIPS_ARGUMENT_REQUIRED_INPUT,
		G_STRUCT_OFFSET(VipsForeignLoadPngFile, filename),
		NULL);
}

static void
vips_foreign_load_png_file_init(VipsForeignLoadPngFile *file)
{
}

typedef struct _VipsForeignLoadPngBuffer {
	VipsForeignLoadPng parent_object;

	/* Load from a buffer.
	 */
	VipsBlob *blob;

} VipsForeignLoadPngBuffer;

typedef VipsForeignLoadPngClass VipsForeignLoadPngBufferClass;

G_DEFINE_TYPE(VipsForeignLoadPngBuffer, vips_foreign_load_png_buffer,
	vips_foreign_load_png_get_type());

static int
vips_foreign_load_png_buffer_build(VipsObject *object)
{
	VipsForeignLoadPng *png = (VipsForeignLoadPng *) object;
	VipsForeignLoadPngBuffer *buffer = (VipsForeignLoadPngBuffer *) object;

	if (buffer->blob &&
		!(png->source = vips_source_new_from_memory(
			  VIPS_AREA(buffer->blob)->data,
			  VIPS_AREA(buffer->blob)->length)))
		return -1;

	if (VIPS_OBJECT_CLASS(vips_foreign_load_png_buffer_parent_class)
			->build(object))
		return -1;

	return 0;
}

static gboolean
vips_foreign_load_png_buffer_is_a_buffer(const void *buf, size_t len)
{
	VipsSource *source;
	gboolean result;

	if (!(source = vips_source_new_from_memory(buf, len)))
		return FALSE;
	result = vips_foreign_load_png_source_is_a_source(source);
	VIPS_UNREF(source);

	return result;
}

static void
vips_foreign_load_png_buffer_class_init(VipsForeignLoadPngBufferClass *class)
{
	GObjectClass *gobject_class = G_OBJECT_CLASS(class);
	VipsObjectClass *object_class = (VipsObjectClass *) class;
	VipsForeignLoadClass *load_class = (VipsForeignLoadClass *) class;

	gobject_class->set_property = vips_object_set_property;
	gobject_class->get_property = vips_object_get_property;

	object_class->nickname = "pngload_buffer";
	object_class->description = _("load png from buffer");
	object_class->build = vips_foreign_load_png_buffer_build;

	load_class->is_a_buffer = vips_foreign_load_png_buffer_is_a_buffer;

	VIPS_ARG_BOXED(class, "buffer", 1,
		_("Buffer"),
		_("Buffer to load from"),
		VIPS_ARGUMENT_REQUIRED_INPUT,
		G_STRUCT_OFFSET(VipsForeignLoadPngBuffer, blob),
		VIPS_TYPE_BLOB);
}

static void
vips_foreign_load_png_buffer_init(VipsForeignLoadPngBuffer *buffer)
{
}

#endif /*HAVE_SPNG*/
